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Reduction of Light-Induced Dark Conductivity of Organic Photocon Ductors

IP.com Disclosure Number: IPCOM000120046D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 4 page(s) / 94K

Publishing Venue

IBM

Related People

Pacansky, J: AUTHOR [+2]

Abstract

Illumination to visible light (500-800 nm) of DEH-based (DEH = 4- diethylaminobenzaldehyde diphenylhydrazone) organic layered photoconductors during the electrophotographic process results in photoconductor electrical fatigue: a decrease in dark charge acceptance and an increase in dark decay rates. This article addresses a simple modification in the formulation of the charge transport layer (CTL), which inhibits this type of electrical fatigue.

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Reduction of Light-Induced Dark Conductivity of Organic Photocon
Ductors

      Illumination to visible light (500-800 nm) of DEH-based
(DEH = 4- diethylaminobenzaldehyde diphenylhydrazone) organic layered
photoconductors during the electrophotographic process results in
photoconductor electrical fatigue:  a decrease in dark charge
acceptance and an increase in dark decay rates.  This article
addresses a simple modification in the formulation of the charge
transport layer (CTL), which inhibits this type of electrical
fatigue.

      The charge transport layer is typically composed of a charge
transport molecule (such as DEH) which is embedded in a polymeric
matrix.  The polymeric matrix is typically a blend of various
polymers which optimize the overall initial mechanical and electrical
properties of the CTL, and they are a polycarbonate, a polyester, and
polyacrylate/polymethacrylate.

      The component in the CTL primarily responsible for
light-induced dark conductivity has been identified as the acid
endgroups of the polyester; light-induced dark conductivity may be
inhibited by elimination of the acid endgroups.  In a typical CTL
formulation, the polyester comprises Z20% of the total weight of the
CTL.  Thus, polyester content and, therefore, acid endgroup content
are significant.  In order to illustrate the extreme sensitivity of
the DEH/polyester mixture to light, consider CTL formulations whereby
the polyester is the sole polymer host into which DE...